1. Field of the Invention
The field of the present invention relates to flashlights and flashlight components.
2. Background
Various flashlight designs are known in the art. Flashlights typically include one or more dry cell batteries. In certain designs, the batteries are arranged in series in a battery compartment of a barrel or tube that acts as a handle for the flashlight. An electrical circuit is frequently established from one electrode of the battery or batteries through a conductor to a switch, then through a conductor to one electrode of the lamp bulb. After passing through the filament of the lamp bulb, the electric circuit emerges through a second electrode of the lamp bulb in electrical contact with a conductor, which in turn is in electrical contact with the other electrode of the battery or batteries. Actuation of the switch to complete the electric circuit enables electricity to pass through the filament, thereby generating light which is typically focused by a reflector to form a beam of light.
The production of light from such flashlights has often been degraded by the quality of the reflector used and the optical characteristics of any lens interposed in the beam path. As a result, efforts at improving such flashlights have often attempted to address the quality of their optical characteristics. For example, more highly reflective, well-defined reflectors have been found to provide a better-defined focus thereby enhancing the quality of the light beam produced. Additionally, several advances have been achieved in the light emitting characteristics of flashlight lamp bulbs.
Despite such efforts, light beams produced by known flashlights are frequently elliptical or elongated in shape. These aberrations generally result from the fact that the flashlight lamp bulb is not properly aligned with the principal axis of the reflector of the assembled flashlight.
In various flashlight designs, the lamp is supported within the flashlight by a holder or spacer within the barrel and extends into the flashlight reflector. Due to manufacturing and assembly operations and tolerances, however, after manufacture of the flashlight is fully completed, the lamp may be permanently misaligned with the reflector, resulting in degraded performance. Furthermore, simply locating the center of the lamp bulb on the principal axis of the reflector does not ensure that aberrations in the projected light beam will be eliminated. This is because the critical component of the lamp that must be centered relative to the reflector is the lamp filament.
One attempt at addressing the misalignment problem is described in U.S. Pat. No. 5,260,858, by A. Maglica. This patent describes a flashlight that includes a switch housing that partially floats within the barrel of the flashlight to allow for slight movement of the lamp relative to the reflector, thereby helping to ensure that the lamp and the lamp filament are centered relative to the reflector. However, in the centering mechanism described in U.S. Pat. No. 5,260,858, to the extent that the lamp filament is not centered within the bulb, then the lamp filament will not be properly centered within the reflector and optimal performance of the flashlight will not be achieved.
Switch designs that are adapted to close an electrical path between the lamp bulb and battery, or batteries, in response to axial movement of the head along the barrel and to open the electrical path in response to axial movement in the opposite direction along the barrel are known. While such switches have generally worked well for flashlights that employ smaller batteries of the AA or AAA type, known designs are not well suited for flashlights that employ larger battery sizes, such as C or D size batteries. One reason such designs are not well suited for flashlights employing larger batteries is that the positive electrode of the battery closest to the head end of the flashlight is urged against a conductor mounted flush against the bottom of the switch. As a result, the battery or batteries may become damaged in the event that the flashlight is dropped. The problem also becomes more acute as the number of batteries connected in series increases due to the added weight, and hence momentum, of the batteries. Another reason such switch designs are not well suited for flashlights with larger batteries is that they are not designed to handle the heat associated with higher amperage lamp bulbs rated for use with such batteries.
Current switch designs that open and close in response to axial movement of the head assembly along the barrel are also not designed to ensure that the filament of each bulb will always be properly aligned with the principal axis of the reflector. As a result, optimal performance of such flashlights is not always achieved.
Misalignment problems are likely to be more pronounced in flashlights with higher capacity bulbs, because such bulbs tend to be longer, thus accentuating any misalignment between the bulb holding mechanism of the flashlight and the reflector as well as any misalignment of the bulb filament within the bulb itself.
The development of flashlights having a variable focus, which produces a beam of light having variable dispersion, has also been accomplished. In such flashlights, the head assembly is typically rotatably connected to the barrel of the flashlight at the end where the bulb is retained. In addition, the head assembly is adapted to be controllably translatable along the barrel such that the relative positional relationship between the reflector and lamp bulb may be varied, thereby varying the dispersion of the light beam emanating through the lens from the lamb bulb. While variable focus flashlights have also employed switches that are adapted to open and close in response to the axial movement of the head assembly, such flashlights have generally been limited to flashlights employing AA and AAA batteries for a variety of reasons, including some of those described above.
In metal flashlights, the flashlight's tail cap is typically a component of the electrical circuit and there must be electrical continuity from one part of the tail cap to another, usually from an outer peripheral region to an inner peripheral region. In such designs when the tail cap and the barrel are anodized, painted, or otherwise treated so that the surface of the tail cap or the barrel loses all or a part of its ability to conduct current, then extra processing steps are required to either remove the non-conducting coating from electrical contact points or mask the contact points prior to forming the coating.
In order to avoid having to remove the nonconductive coating from the contact points of the tail cap, or mask the contact points, attempts have been made to eliminate the tail cap from the electrical circuit. Several different designs have been employed to achieve this end. Such designs, however, have required the use of a plurality of parts and multiple manufacturing steps. The elimination of any such parts and steps would decrease the overall manufacturing cost of the flashlight, as well as improve the reliability of the flashlight.